The present invention concerns methods and compositions for the improvement of skin appearance by topical application of a cosmetic formulation in the form of a pad, which contains a skin permeation enhancer consisting of a plant polar lipid.
Skin forms a barrier between the internal organs of the body and the environment. The condition of the skin reflect the health and youthfulness of the individual. Consequently, it is desirable to enhance these skin properties particularly in aging individuals. Active agents have been identified that have some beneficial effect on skin when applied as a cream or ointment although this beneficial effect is limited by the ability of the active agent to penetrate through the stratum corneum of the epidermis to the basal cells below. The epidermis of the skin has a thickness of about 0.1 mm with a layer of keratinized cells at the surface and a basal layer that continually produces new cells in a cycle of cell growth and cell death. (FIG. 1). It is desirable to develop a cosmetic formulation, which when applied to the surface of the skin, provides increased penetration of active ingredients to the basal layer. To improve skin penetration of topically administered agents, synthetic chemical substances have been added to the cosmetic formulations as penetration enhancers such as alcohols, polyalcohols and various surfacatants. These chemicals have some efficacy although they may be accompanied by undesirable side effects such as skin irritation or an immune reaction. There is therefore a need for enhancers which are capable of improving the penetration of active agents to the basal layer of the skin without causing an immune response or unpleasant irritation.
Although cosmetics are commonly delivered to the target site in the form of a cream or ointment, patch-type delivery systems have been developed for topical delivery of cosmetics. Typically, these patches include an adhesive layer, multiple polymer layers containing reagents and a backing layer. EP 0410921 A2 describes a dressing for transcutaneous application of active substances for both therapeutic and cosmetic purposes which has five layers, but apparently lacks enhancers. The reference describes the use of these dressings for the delivery of any cosmetic or therapeutic active agent of vegetable, chemical, pharmacological and biological origin. In contrast, GB 2 265 086 is directed specifically to topical administration of skin whitening agents where a three or five layer system contains active agent, enhancers, and stabilizers in the adhesive layer. In this system, the release and absorption of the active ingredients through the skin was achieved by utilizing high concentrations of permeation enhancers. Indeed, the concentration of permeation enhancer used in this reference was as much as sixfold that of the active agent.
Other skin cosmetic compositions in the form of patches are disclosed in WO 96/14822 and the corresponding U.S. Pat. No. 5,784,978 for improving the appearance of skin. This reference utilizes ascorbic acid as the active agent in optional combination with moisturizers contained in a patch analogous to a transdermal patch. The reference lists a number of compounds for use as penetration enhancers in transdermal patches as used for systemic delivery citing Pfister and Hseih (1990) Pharmaceutical Technology, September 1990 and October 1990.
There is a need for a cosmetic patch or pad that is directed to topical delivery of active agent rather than systemic delivery and provides enhanced penetration of active agents to the basal layer of the skin. The enhancer should possess desirable physicochemical properties, with minimum undesirable skin reactions, while at the same time being cost effective and readily manufactured. A benefit of such an enhancer would be to reduce the concentration of active ingredients without reducing the overall effectiveness of the patch.
This invention satisfies the above needs. A novel device for improving skin appearance is provided. In preferred embodiments of the invention, a device for the improvement of skin appearance is provided that includes a pad having a backing layer, a vehicle and a release layer, the vehicle being located therebetween, the vehicle including a cosmetic formulation and a skin permeation enhancer, wherein the skin permeation enhancer includes a plant polar lipid. The plant polar lipid can be for example, a phospholipid or a glycolipid. More particularly, the plant polar lipid may include a ceramide preparation including at least one of a ceramide and a glycoceramide. In an embodiment of the invention, the ceramide preparation contains at least 50% ceramide and glycoceramide, more particularly, the enhancer is present in a range of 0.1%-5% w/w of the cosmetic formulation. In a preferred embodiment, the permeation enhancer is formulated in the absence of a synthetic lipid and in the absence of a surfactant.
The cosmetic formulation may further include a cosmetic active agent and at least one of an antimicrobial agent, an antioxidant, a preservative, an anti-irritant, a plasticizer and a solubilizer such that the concentration range of the cosmetic active agent may be in the range of 1 to 20% w/w, the anti-microbial agent in the range of 0 to 5% w/w, the anti-oxidant is 0 to 4% w/w, the preservative in the range of 0 to 5% w/w, the anti-irritant in the range of 0 to 7% w/w, the plasticizer in the range of 0-10% w/w, and the solubilizer in the range of 0 to 5% w/w. Examples of cosmetic agent for incorporation into the device include anti-hyperpigmentation agents, anti-blotching agents, anti-aging agents, eye contour agents, slimming agents, anti-cellulite agents, soothing agents, sunburn agents, anti-irritating agents, skin firming agents, anti-elastase agents, anti-collagenase substances, free radical scavengers, seboregulators, hydratives, and AHA (xcex1-hydroxy acid) agents, vitamins, anti-oxidants, anti-irritants and minerals.
In a further embodiment of the invention, a method is provided for delivering a cosmetic agent to a topical target site for improving skin appearance, that includes (a) selecting a multilaminate device including a backing layer, a vehicle and a release liner; (b) providing the cosmetic agent and an enhancer for dispersion within the vehicle wherein the enhancer is a plant polar lipid including a sphingolipid, more particularly a ceramide preparation; and (c) forming a device for improvement of skin appearance.
In a further embodiment of the invention, the cosmetic agent for improving skin appearance may be selected so as to achieve any of the following: increased skin elasticity, decreased wrinkles, removal of pimples, reduction in cellulitis, increased skin moisture, regulation of sebum secretion, reduced hyperpigmentation and blotching.